2cEnergy and voltage in circuits

Syllabus objectives

• 2.7explain why a series or parallel circuit is more appropriate for particular applications, including domestic lighting
• 2.8understand how the current in a series circuit depends on the applied voltage and the number and nature of other components
• 2.9describe how current varies with voltage in wires, resistors, metal filament lamps and diodes, and how to investigate this experimentally
• 2.10describe the qualitative effect of changing resistance on the current in a circuit
• 2.11describe the qualitative variation of resistance of light-dependent resistors (LDRs) with illumination and thermistors with temperature
• 2.12know that lamps and LEDs can be used to indicate the presence of a current in a circuit
• 2.13know and use the relationship between voltage, current and resistance: voltage = current × resistance V = I × R
• 2.14know that current is the rate of flow of charge
• 2.15know and use the relationship between charge, current and time: charge = current × time Q = I × t
• 2.16know that electric current in solid metallic conductors is a flow of negatively charged electrons
• 2.17understand why current is conserved at a junction in a circuit
• 2.18know that the voltage across two components connected in parallel is the same
• 2.19calculate the currents, voltages and resistances of two resistive components connected in a series circuit
• 2.20know that: • voltage is the energy transferred per unit charge passed • the volt is a joule per coulomb
• 2.21know and use the relationship between energy transferred, charge and voltage: energy transferred = charge × voltage E = Q × V